$width:3000px;
$height:400px;

  .box1{
  height:$height ;width: $width;
    .box2{
      height:$height ;width: $width;
        .box3{
          height:$height ;width: $width;
          .box4{
            height:$height ;width: $width;font-size: 12px;
            background: yellow;
          }
        }
    }
  }
$obwidth:300px;
$obheight:500px;
.bos{
 width:$obwidth;
  height:$obwidth;
  &-title{
    width:$obwidth;
    height:$obwidth;
  }
  &--conter{
    width:$obwidth;
    height:$obwidth;
  }
  &-bottom{
    width:$obwidth;
    height:$obwidth;
  }
}

$wenzicolor:#ccc;

.box{
  background:$wenzicolor;
}